The inital RSA key generation is done the CPU. An ivybridge i7 can generate 51 keys per second using a single core. Each key can provide 1 gigahash worth of exponents to mine and a decent CPU can keep up with several GPUs as it is currently implemented.

6. Encoding onion addresses [ONIONADDRESS]
The onion address of a hidden service includes its identity public key, a
version field and a basic checksum. All this information is then base32
encoded as shown below:
onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion"
CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2]
where:
- PUBKEY is the 32 bytes ed25519 master pubkey of the hidden service.
- VERSION is an one byte version field (default value '\x03')
- ".onion checksum" is a constant string
- CHECKSUM is truncated to two bytes before inserting it in onion_address
Here are a few example addresses:
pg6mmjiyjmcrsslvykfwnntlaru7p5svn6y2ymmju6nubxndf4pscryd.onion
sp3k262uwy4r2k3ycr5awluarykdpag6a7y33jxop4cs2lu5uz5sseqd.onion
xa4r2iadxm55fbnqgwwi5mymqdcofiu3w6rpbtqn7b2dyn7mgwj64jyd.onion
For more information about this encoding, please see our discussion thread
at [ONIONADDRESS-REFS].

Tor as of version 0.3.2.1-alpha supports the next-gen onion services protocol for clients and services! As part of this release, ​the core of proposal 224 has been implemented and is available for experimentation and testing by our users.

The address for our Onion Service is:https://www.nytimes3xbfgragh.onion/

讓所有人想看到的人都有辦法看到是紐約時報的目標，所以就推出了許多不一樣的方式讓使用者可以看到內容...

The Times is dedicated to delivering quality, independent journalism, and our engineering team is committed to making sure that readers can access our journalism securely. This is why we are exploring ways to improve the experience of readers who use Tor to access our website.

OnionShare lets you securely and anonymously share files of any size. It works by starting a web server, making it accessible as a Tor onion service, and generating an unguessable URL to access and download the files. It doesn't require setting up a server on the internet somewhere or using a third party filesharing service. You host the file on your own computer and use a Tor onion service to make it temporarily accessible over the internet. The other user just needs to use Tor Browser to download the file from you.

用法的部份就更清楚了：

Open OnionShare, drag and drop files and folders you wish to share into it, and click Start Sharing. After a moment, it will show you a .onion URL such as http://asxmi4q6i7pajg2b.onion/egg-cain. This is the secret URL that can be used to download the file you're sharing.

CAs MUST NOT issue a Certificate that includes a Domain Name where .onion is in the right-most label of the Domain Name with a validity period longer than 15 months. Despite Section 9.2.1 of the Baseline Requirements deprecating the use of Internal Names, a CA MAY issue a Certificate containing an .onion name with an expiration date later than 1 November 2015 after (and only if) .onion is officially recognized by the IESG as a reserved TLD.

然後：

On or before May 1, 2015, each CA MUST revoke all Certificates issued with the Subject Alternative Name extension or Common Name field that includes a Domain Name where .onion is in the right-most label of the Domain Name unless the Certificate was issued in compliance with this Appendix F.

If Facebook has the resources to brute force their own full key, then you better believe the NSA and GCHQ do too. Which means that you will no longer know if the hidden service you're connecting to is the real one or the NSA/GCHQ version. Tor hidden services are now dead.